1. Instructors: Winston Hsu, Hao-Hua Chu Fall 2011
HW3: Heap-File Page
Instructors: Winston Hsu, Hao-Hua Chu
Fall 2011
This document is supplementary document that was created by referring Minibase Project of Univ. of Wisconsin
The slide refers to

2. Architecture of a DBMS Query Query Optimization and Execution
Relation Operators
File and Access Methods
Buffer Management
Disk Space Management DB

3. Minibase Relational Database Management System (RDBMS)
made by Wisconsin University for educational purpose
Independent implementation of each component is possible
No pain to implementing whole DBMS
Suitable to understand the internal architecture of DBMS
Components
Parser / Optimizer / Query Processor/ Heap file / B+-tree index / Buffer pool manager / Disk space management system

4. Heap-File Page Simple Heap-File Page Structure Operations
Heap-File Page consists of page information, data area and slot array.
Data area in a Heap-File Page is always compacted.
We assume that the supported record data type is only character.
Operations
Insert / Delete a record in a heap-file page
Get a first / next record id
Get the data / pointer of a record
Get some information

5. HFPage Structure Page Information Data Area record … … … … … … freePtr
short slotCnt;
short freePtr;
short freeSpace;
short type;
PageId prevPage;
PageId nextPage;
PageId curPage;
Page Information
Data Area
record … … … … … …
freePtr
// -1 if EMPTY SLOT
short length;
// offset from data[0]
short offset; … … … … … … …
slot[0]

6. insertRecord(case 1) Page Information Page Information Data Area… …
record
Data Area … … … … … …
Inserted record … … … …
empty … …
Inserted slot … …
slot[0]
slot[0]

7. insertRecord(case 2) Page Information Page Information record
Data Area … …
record
Data Area … … … … … …
Inserted record …
Inserted slot … … … … … … …
slot[0]
slot[0]

8. deleteRecord Page Information Page Information Data Area record …
Removed record
Data Area
record … … … … … … … …
Removed slot … …
empty …
slot[0]
slot[0]

9. exchangeRecord Page Information Page Information Data Area ABC … …
ABCDE
Data Area … … …
ABCDE … …
ABC … … …
slot[2] … …
slot[2] …
slot[0]
slot[0]

10. Return Values of APIs
Status insertRecord(char *recPtr, int recLen, RID& rid);
If there is not enough space for new record, return DONE
Status firstRecord(RID& firstRid);
If there is no record in Page, return DONE
Status nextRecord (RID curRid, RID& nextRid);
If there is no next record in Page, return DONE
Others
if slotNo or pageNo of a record Id and input parameters are not appropriate, return FAIL

11. Other int HFPage::available_space(void)
sizeof(slot_t) bytes must be reserved for a new slot and cannot be used by a new record.
freePtr specifies the offset of the first free bytes in data[]
Insert from it
Modify it when deleting
Check the output with sample_output
“dumpPage, this: 0x7fffbcf7fa20” is a pointer value. Ignore it.
diff your_output sample_output
If there are any questions, you can post them on ptt.cc / CSIE_DBMS.

12. All You have to do
hfpage.C

13. Try and Test
wget
tar -xvvzf hfpage11.tar.gz
make
hfpage
test_driver.C
Test code file